Sir Alex Ferguson has revealed he turned down the England manager's job on two separate occasions during his Manchester United reign.

The Scot states in his autobiography, which is released on Thursday, that he was asked to become England boss in succession to Glenn Hoddle and Kevin Keegan.

Ferguson rejected the offers out of hand, though, saying: "There was no way I could contemplate that. It wasn't a bed of nails I was ever tempted to lie on."The fact that he was offered the England job on two occasions will raise eyebrows in some quarters, although there will be little surprise that, as a proud Scot, he rejected the approaches.

Ferguson, who managed United for 27 successful years before retiring in the summer of 2013, discusses a wide range of topics in the book, called 'My Autobiography'.

The Scot reflects on his rivalries with Liverpool, Manchester City, Chelsea and Arsenal and discusses his relationship with a number of players that have come and gone through the doors at Old Trafford since he arrived from Scotland in 1986.

Former United captain Roy Keane comes in for criticism in the book, which follows on from his last autobiography spanning from 2000-2013.

Keane became one of the trusted pillars of Ferguson's reign at Old Trafford when he moved from Nottingham Forest in 1993, but their relationship soured 12 years later.

Ferguson reveals that Keane was livid at the club over their pre-season training camp in Portugal. The Irish midfielder said the accommodation was not up to scratch.

Then Keane tore into his team-mates in an interview with the club's in-house TV station MUTV.

Ferguson says in the interview, which was pulled, Keane "slaughtered" several of the club's senior players.

Keane then suggested the squad watch the interview and a furious row ensued. Ruud van Nistelrooy, Edwin van der Sar and Carlos Queiroz all argued and Keane then accused Ferguson of bringing his own dispute with shareholder John Magnier over the Rock of Gibraltar racehorse into the club.

"It was frightening to watch. And I'm from Glasgow," Ferguson says.

"He has the most savage tongue you can imagine."

Ferguson sold Keane to Celtic. The Irishman returned to Carrington to apologise to Ferguson months later, but the two have clashed since.

In a press conference that lasted almost 45 minutes, Ferguson touched on a number of key areas in his book, including the revelation that he twice turned down the job of managing England.

"It was a great opportunity to relegate England,'' said Ferguson.

"No way would I have taken that job. (Former FA chief executive) Adam Crozier was the first one to come and see me.

"It took me about 10 seconds to say no way. I couldn't manage England in a million years. Think of me going back to Scotland doing that.''

Three of the more controversial characters Ferguson had to deal with during his 26 years at United were Wayne Rooney, Keane and David Beckham.

Ferguson repeated his assertion that Rooney asked to leave United at the end of last season.

However, he also stated that had the England forward been playing the way he has been this season, a move away from Old Trafford would not even have been considered.

"Wayne asked away because he felt he was playing out of position,'' said Ferguson.

"I can understand that. My judgement was that Wayne wasn't playing well enough.

"But when you see him playing like he is, do you think I would drop him? No way.

"He is England's great white hope and a great player for Manchester United. The player who is playing now is a different player.''

Rooney also receives criticism, although on a far lesser scale. Ferguson laments the striker's failure to "absorb new ideas or methods quickly" in training and his supposed lack of fitness.

Ferguson does not go into much detail about how Rooney asked to leave United last summer - only saying that the striker was unhappy at being left on the bench so often.

He does reveal more about Rooney's plea to leave in 2010, when the former Everton man told Ferguson that the club were not ambitious enough. Rooney said Ferguson should have signed Mesut Ozil, now at Arsenal.

Ferguson writes in the book: "My reply was that it was none of his business who we should have gone for."

Like Rooney, Beckham was also a big part of Ferguson's reign at Old Trafford.

Just like in his first autobiography, Ferguson talks about how disappointed he was to see Beckham regarded as a celebrity.

The Scot talks about his annoyance at the interest in Beckham's hair and not his performances on the pitch.

Ferguson also talks about the infamous moment, after an FA Cup game against Arsenal, in which he kicked a boot in the United dressing room that struck Beckham above the eye, requiring him to have stitches.

"David swore. I moved towards him, and as I approached I kicked a boot. It hit him right above the eye," Ferguson says.

Ferguson told Beckham he had let his team-mates down in the match and said that he decided to sell the former England captain shortly afterwards.

Van Nistelrooy comes in for more criticism than most in the book. The Scot reveals that the striker asked to leave just three days before the FA Cup final of 2005. He stayed, but after a training ground bust-up with Cristiano Ronaldo, Ferguson said he had no choice but to sell the Dutchman, who has since apologised to his former boss.

Ferguson also revealed Van Nistelrooy swore at him after telling the Dutchman he would not be brought off the bench in the League Cup final of 2006.

Naturally, Ferguson's enemies come in for criticism in the book. Sheikh Mansour's purchase of Manchester City in 2008 gave Ferguson a new rival once the club became a force under Roberto Mancini.

Ferguson describes the day City won the title at United's expense as the worst of his life.

The Scot also has a dig at Mancini in the book, criticising his decision to keep Carlos Tevez on the books after the Argentinian refused to come off the bench in the club's Champions League game at Bayern Munich.

Mancini is not the only manager to receive criticism from Ferguson. Arsene Wenger, a big adversary for Ferguson, joked he was "fearing the worst" prior to the release of the book.

Unlike in his first autobiography, Ferguson has a much more measured view of the Frenchman. Ferguson says the pair are now very good friends, rather than enemies.

There was one exception, however. In October 2004 when United ended Arsenal's 49-match unbeaten run, Ferguson was left covered in pizza following a furious row between staff and players from both teams.

The row came after Ruud van Nistelrooy claimed Wenger berated him as he left the pitch. Ferguson says he does not know who threw the pizza, but claims Wenger's "fists were clenched" when the Scot confronted him over Van Nistelrooy's claims.

Ferguson also touches on his relationship with several Liverpool managers. He condemns Graeme Souness as "impetuous" while he also criticises Kenny Dalglish's decision to spend £20million on Stewart Downing.

The most candid observation about Liverpool from Ferguson comes when he talks about Rafael Benitez.

Ferguson wrote to Benitez congratulating him on winning the 2005 Champions League, but four seasons later the pair clashed.

With Liverpool leading United by seven points in January 2009, Ferguson claimed the Merseysiders could get nervous in the home straight.

That caused Benitez to lash out at Ferguson in a press conference over his conduct towards referees.

Ferguson says such a move was "silly", adding: "The mistake he made was to turn our rivalry personal."

Two managers who receive widespread praise in the book are Ferguson's successor David Moyes and Jose Mourinho.

Ferguson says he met with co-chairman Joel Glazer in the winter of 2012 when he decided to retire and the Scot says they both had no doubt that Moyes was the right man to take the reins at Old Trafford.

Mourinho, with whom Ferguson is close, also comes in for praise from the former United boss, although he admits he was taken aback by the Portuguese's decision to anoint himself as 'The Special One'.

till I suppose it still gives him at least another year in the job. By the time it comes around , he can always make up another excuse. First it was 3 months , then a year .....Next year ? Whats his excuse with Van Persie ?